A low-noise multi-channel device for the monitoring of systemic electrical signal propagation in plants.

Long-distance electrical signals generated in locally stimulated plants are linked with systemic physiological responses. The propagation of electrical signal through a plant can be measured by multiple electrodes attached to different sites of a plant body. As this signal has to be measured with the sensitivity of tens of microvolts, it can be easily disturbed by power-line hums or external electromagnetic fields. These disturbances can mimic the action potentials generated by a plant. In this work, we present a brief summary of various experimental approaches to the measurement of surface electrical potential (SEP) on a plant and a description of our multi-channel device for the SEP measurement. The main advantages of our measuring system are galvanic separation of the measuring unit, resulting in the elimination of power-line disturbances, and simple and stable contact of Ag/AgCl-peletted electrodes with the plant surface, facilitated by an ordinary gel used in human electrocardiography. These improvements enabled us to detect unperturbed variation (slow) and action (fast) potentials on a plant, as demonstrated by the four-electrode measurement of the electrical signal propagation in a locally wounded tomato plant.